Electrical Field Device and Method for Establishing a Data Link Between a Data Interface of the Electrical Field Device and a Data Memory Inside the Device

ABSTRACT

An electrical field device has a microprocessor-controlled control device, a data memory which is inside the device and is connected to the control device via a first memory controller, and a data interface which is connected to the control device and is intended to connect external devices to the electrical field device. In order to ensure access to the data memory inside such a field device even when the control device or internal power supply device is not in working order, the data interface is connected to the data memory inside the device via a second memory controller. There is also disclosed a method for establishing a data link between a data interface of an electrical field device and a data memory inside the device.

Electrical field device and method for establishing a data link betweena data interface of the electrical field device and a data memory insidethe device

The invention relates to an electrical field device having amicroprocessor-controlled control device, a data memory, which is insidethe field device and is connected to the control device via a firstmemory controller, and a data interface which is connected to thecontrol device and is intended for connecting external equipment to theelectrical field device. The invention also relates to a method forsetting up a data link between the data interface of the electricalfield device and the data memory inside the field device.

An electrical field device of this kind is known by way of example fromthe German utility model with the issue number 20 2004 020 653. Theknown electrical field device comprises a microprocessor-controlledcontrol device, a data memory inside the field device and a datainterface connected to the control device. In the known field device,the data interface can have, in particular, external passive datastorage modules, such as a USB stick, connected to it.

Electrical field devices are usually used for picking up measured valuesin automated processes and for controlling such processes. By way ofexample, the processes may be chemical or industrial processes,industrial production processes or distribution processes, for examplefor distributing electrical power in power supply networks. In thiscontext, the electrical field devices are usually arranged close to therespective automated process. In the case of electrical power supplynetworks, the electrical field devices may be control stations orprotective devices, for example. The latter are used to pick up measuredvalues from the power supply network and to check them for compliancewith permitted operating ranges. If the measured values are outside ofthe permitted operating range, countermeasures are automaticallyprompted by the electrical protective device, such as opening a circuitbreaker.

The processes in an electrical field device are usually controlled usingmicroprocessor-controlled control devices, such as an assemblycontaining a central processing unit (CPU). This accesses the fielddevice's internal memory, in which it can store data and from which itcan read an executable program, for example. An executable program ofthis kind may be what is known as firmware in the field device, forexample.

In order to perform all the data processing processes, themicroprocessor-controlled control device and the data memory need to besupplied with electrical power, what is known as auxiliary power of thefield device. This can be provided by a current source in the electricalfield device, for example, such as a battery or—far more commonly—by apower supply unit which is located in the electrical field device andwhich is connected to an external supply of power. If the supply ofpower and/or the control device fails, the data which have been storedin the data memory inside the field device can now be read externallyonly with difficulty.

The object of the invention is to specify an electrical field device anda method for setting up a data link between a data interface in thefield device and a data memory inside the field device, wherein datainterchange with the data memory inside the field device is possibleeven when the field device is not fully operational.

The invention achieves this object for the field device by virtue of thedata interface being connected to the data memory inside the fielddevice via a second memory controller. This is because this not onlyallows the control device itself to be used to access the data memoryinside the field device, but also allows data interchange via the datainterface of the electrical field device, entirely without needing theelectrical field device's control device. By way of example, the datainterface can have an external computer connected to it which is used toaccess the data in the data memory inside the field device.

One advantageous embodiment of the field device according to theinvention involves the data memory inside the field device and the datainterface being connected by means of a power supply line. In this way,if the power supply in the field device fails, the data memory insidethe field device can be supplied with the electrical power required forstoring or reading data via the data interface.

In line with another advantageous embodiment of the field deviceaccording to the invention, a changeover apparatus whose input isconnected to the data interface and whose output is connected to thecontrol device and to the second memory controller, and a monitoringdevice are provided, wherein the monitoring device is designed tomonitor a field device internal power supply and/or the control devicein the electrical field device for functionality and, if the fielddevice's internal power supply and/or the control device fails, promptsthe changeover apparatus to break the link between the data interfaceand the control device and to set up the link between the data interfaceand the second memory controller. This particularly advantageouslyallows automatic changeover of the access path to the data memory insidethe field device. If there is a fault in the electrical field devicewhich concerns the control device or the power supply in the fielddevice, so that access to the data memory inside the field device viathe electrical field device's control device is no longer possible, theaccess path is changed over by the monitoring device and the changeoverdevice such that data interchange can then take place between the datamemory inside the field device and the data interface without theelectrical field device's control device being involved.

Another advantageous embodiment of the electrical field device alsoprovides for the electrical field device to have a removable operatorcontrol unit which comprises at least the data memory inside the fielddevice, the data interface and the second memory controller. In thiscase, the electrical field device is an electrical field device ofmodular design in which the electrical control device is arranged in afirst housing module of the electrical field device and the operatorcontrol elements of the electrical field device, such as a display, akeypad and the data interface, are arranged together with the datamemory inside the field device and the second memory controller in anoperator control module which can be removably connected to the firsthousing module. This special arrangement of the components in the fielddevice allows access to the field device's data memory even if there isno data link between the housing module with the control device and theoperator control unit.

One exemplary embodiment of such a field device of modular design isdescribed in DE 19817945 C1. Such a field device is particularlysuitable for installation in a switchgear cabinet, since in this case itis not necessary to install the entire device in the switchgear cabinetdoor, but rather only the operator control module is mounted on theswitchgear cabinet door and a data line is used for data interchangebetween the operator control module and the first housing module withthe control device which is arranged in the switchgear cabinet.

The object stated above is achieved for the cited method by virtue of amonitoring device monitoring the functionality of a control deviceand/or an internal power supply in the electrical field device; if thecontrol device and/or the internal power supply fails, the monitoringdevice prompts the data link between the control device and the datamemory inside the field device to be broken and a data link between thedata interface and the data memory inside the field device to be set up.In this way, data interchange can particularly advantageously take placewith the data memory inside the field device externally via the datainterface without needing the electrical field device's control device.

It is also considered to be advantageous if the monitoring device uses achangeover switch to prompt the data link between the control device andthe data memory inside the field device to be broken and the data linkbetween the data interface and the data memory inside the field deviceto be set up.

To explain the invention in more detail, some exemplary embodiments areshown merely by way of example in FIGS. 1 to 4, in which

FIG. 1 shows a perspective view of a field device connected to anexternal computer via a data interface,

FIG. 2 shows a schematic block diagram of a first exemplary embodimentof an electrical field device,

FIG. 3 shows a schematic block diagram of a second exemplary embodimentof an electrical field device, and

FIG. 4 shows a schematic block diagram of a third exemplary embodimentof an electrical field device.

FIG. 1 shows an electrical field device 1, which may be an electricalprotective device for protecting electrical power supply networks, forexample. The electrical field device 1 has a housing 2 whose front hasan operator control panel with a display 3, a keypad 4 and a datainterface 5. The data interface 5 is used to connect an external dataprocessing device in the form of a laptop 7 to the electrical fielddevice 1 by means of a data transmission line 6. In this context, thefield device 1 is designed such that, even if, by way of example, acontrol device and/or an internal power supply in the electrical fielddevice 1 are not in operation (e.g. on account of a fault), it ispossible to carry out data interchange between a data memory inside thefield device 1 and the laptop 7 via the data interface 5.

The internal design of the electrical field device 1 is shown in FIG. 2by way of example in a first exemplary embodiment. In this case, theillustration is limited to a schematic block diagram. In FIG. 2, anelectrical field device 20 has a microprocessor-controlled controldevice 21, which is used to perform the functions of the electricalfield device 20. To stipulate such functions, a piece of software (e.g.the device's firmware) is stored in a data memory 22 inside the fielddevice, for example, and, when executed by means of the control device21 in the electrical field device 20, performs the desired functions.

The control device 21 accesses the data memory 22 inside the fielddevice via a first memory controller 23. Although FIG. 2 shows thememory controller 23 in the form of a separate module of the electricalfield device 20, it is also possible for the functionality implementedby the memory controller 23 to be integrated into the control device 21.

The control device 21 is also connected to a data interface 24 which canbe used to connect external equipment to the electrical field device 10.

The electrical power required for controlling the field device'sinternal processes, particularly of the control device 21 and of thedata memory 22 inside the field device, is provided by a power supplydevice 25, for example a power supply unit in the electrical fielddevice 20. In FIG. 2, the power supply device 25 is connected firstly tothe control device 21 and secondly to the data memory 22 inside thefield device by means of lines 26 a and 26 b.

If either the power supply device 25 or the control device 21 in theelectrical field device 20 fails, the control device 21 and the firstmemory controller 23 can no longer be used to access the data memory 22inside the field device. In order nevertheless to be able to store datain the data memory 22 inside the field device or to read them from it,the data interface 24 is connected to the data memory 22 inside thefield device via a second memory controller 27. In this way, the datainterface 24 can be used for directly accessing the data memory 22inside the field device, without this requiring the control device 21 inthe electrical field device 20.

If the data memory 22 inside the field device requires electrical powerfor storing and/or reading data, the data interface 24 is connected tothe data memory 22 inside the field device by means of a power supplyline 28. Thus, the data memory 22 inside the field device can beprovided with the electrical power required for the storage and readingoperations via the data interface 24 and the power supply line 28.

In this way, the data memory 22 inside the field device in theelectrical field device can be accessed externally without there beingany need for the control device or the internal power supply in theelectrical field device to be operational. Apart from when one of thesetwo components fails, this may also arise, by way of example, when theelectrical field device has not yet been definitively connected andhence, by way of example, there is not yet an external supply of powerfor the field device's internal power supply 25. By way of example, theelectrical field device 20 allows access to the data memory 22 insidethe field device, for example in order to perform an update for thefirmware or to set parameters, even when it is in its transportpackaging. This merely requires the data interface 24 of the electricalfield device 20 to be externally accessible.

FIG. 3 shows a second exemplary embodiment of an electrical fielddevice. The fundamental components of the electrical field device 30shown in FIG. 3 correspond to those of the field device 20 shown in FIG.2, with identical components being identified by the same referencesymbols. Thus, the field device 30 shown in FIG. 3 also has amicroprocessor-controlled control device 21, a field device internalpower supply 25, a data memory 22 inside the field device, a datainterface 24 and also a first memory controller 23 and a second memorycontroller 27. The field device 30 shown in FIG. 3 differs from thefield device 20 shown in FIG. 2 by virtue of a changeover apparatus 31whose input is connected by means of a first connection 31 a to the datainterface 24 and whose output is connected firstly by means of a secondconnection 31 b to the control device 21 and secondly by means of athird connection 31 c to the second memory controller 27. Internally,the changeover apparatus 32 allows switchable electrical connectioneither of the connections 31 a and 31 b or of the connections 31 a and31 c, so that the data interface 24 is connected either to the controldevice 21 of the electrical field device 30 or to the second memorycontroller 27.

The field device 30 shown in FIG. 3 also has a monitoring device 32which, as indicated by the dashed lines 33 a and 33 b, is used tomonitor the control device 21 and the internal power supply 25 of theelectrical field device 30 for their functionality. Unlike in theillustration shown in FIG. 3, it is also possible to monitor just one ofthe two components, that is to say either the control device 21 or thepower supply 25, or else additional components of the electrical fielddevice 30 (e.g. a data bus or the first memory controller 23), by meansof the monitoring device 32. If the monitored components of theelectrical field device 30 are functional, the changeover apparatus 31is actuated by means of the monitoring device 32 such that the datainterface 24 is connected to the control device 21. This allows the datainterface 24 to be actuated by the control device 21 of the electricalfield device 30, for example in order to use the control device 21 tostore or read data in or from an external data storage module, such as aUSB stick, connected to the electrical field device 30 via the datainterface 24. In addition, in this operating position, the datainterface 24 can also be used to connect an external data processingdevice, such as the laptop 7 shown in FIG. 1, to the electrical fielddevice, with all communication by the electrical field device 30 withthe external data processing device being controlled by the controldevice 21.

If at least one of the two monitored components of the electrical fielddevice 30 has failed or is not operational for other reasons, thechangeover device 31 is actuated by means of the monitoring device 32such that the data interface 24 is then connected to the data memory 22inside the field device via the second memory controller 27. In thisposition of the changeover apparatus 31, the data interface 24 can beused to access the data memory 22 inside the field device directly,without this requiring the electrical field device's control device 21to be active.

Since failure of the field device's internal power supply 25 willusually also mean that the monitoring device 32 is without electricalpower, either changing over the changeover apparatus 31 requires themonitoring device 32 to be provided with an electrical energy buffer,for example a capacitor, which allows the monitoring device 32 tocontinue to be supplied with power, even after the field device'sinternal power supply 25 has failed, for as long as necessary in orderto perform a changeover operation on the changeover apparatus 31, or,alternatively, the changeover apparatus 31 may also be in a form suchthat when it is without power it automatically sets up a link betweenits connections 31 a and 31 c, so that the data interface 24 is alwaysconnected to the data memory 22 inside the field device via the secondmemory controller 27 when there is no power, without the need for themonitoring device 32 to perform an active switching operation.

Although the monitoring device 32 and the changeover apparatus 31 shownin FIG. 3 are shown as separate components, it is also possible for themto be integrated into a single component.

Finally, FIG. 4 shows another exemplary embodiment of an electricalfield device. As shown in FIG. 4, an electrical field device 40comprises two modules, namely a housing module 40 a, which contains thecontrol device 21, the first memory controller 23 and the internal powersupply 25, and an operator control unit 40 b, which comprises the datamemory 22 inside the field device, the second memory controller 27, thedata interface 24, the monitoring device 32 and the changeover apparatus31. The housing module 40 a may be a field device basic module, forexample, in which the essential functions of the electrical field deviceare performed. For this, the housing module 40 a contains the controldevice 21. By way of example, the operator control unit 40 b may be anoperator control unit of the kind which can be fitted onto and removedfrom the housing module 40 a.

Such a design is particularly suitable when such a field device 40 isinstalled in a switchgear cabinet. Since the operator control elementsof the electrical field device 40 are also meant to be accessible fromthe outer side of the switchgear cabinet door, it would usually benecessary to install the complete field device in the switchgear cabinetdoor. With a field device of modular design, however, only the operatorcontrol unit 40 b of the electrical field device 40 needs to beinstalled in the switchgear cabinet door, while the field device basicmodule or the housing module 40 a is arranged inside the switchgearcabinet and is connected to the operator control module 40 b by means ofappropriate data lines.

So that it is possible to read from and write to the data memory insidethe field device in a field device of modular design even when the basicdevice is not operational or when the basic device and the operatorcontrol module are not connected to one another, the operator controlunit 40 b contains the data memory 22 inside the field device, thesecond memory controller 27, the data interface 24 and also thechangeover apparatus 31 and the monitoring apparatus 32. As alreadydescribed in relation to FIG. 3, the data memory 22 can be accessed viathe data interface 24. The device modules 40 a and 40 b need to haveelectrical lines provided between them in order to make at least theconnections indicated in FIG. 4 between the housing module 40 a and theoperator control unit 40 b.

1-6. (canceled)
 7. An electrical field device, comprising: a microprocessor-controlled control device; an internal data memory and a first memory controller connecting said data memory to said control device; a data interface connected to said control device and configured for connecting external equipment to the electrical field device; and a second memory controller connecting said data interface with said internal data memory inside the field device.
 8. The electrical field device according to claim 7, wherein said internal data memory and said data interface are connected by way of a power supply line.
 9. The electrical field device according to claim 7, which further comprises: a changeover apparatus having an input connected to said data interface and an output connected to said control device and to said second memory controller; a field device-internal power supply; a monitoring device configured to monitor at least one of said power supply and/or said control device for functionality and, if said power supply and/or said control device fails, to prompt said changeover apparatus to break a link between said data interface and said control device and to set up a link between said data interface and said second memory controller.
 10. The electrical field device according to claim 7, which comprises a removable operator control unit comprising at least said internal data memory, said data interface, and said second memory controller.
 11. A method for setting up a data link between a data interface in an electrical field device and a data memory inside the field device, which comprises the following steps: monitoring, with a monitoring device, a functionality of a control device and/or of an internal power supply in the electrical field device; if the control device and/or the internal power supply fails, prompting, with the monitoring device, the data link between the control device and the data memory inside the field device to be broken and a data link between the data interface and the data memory inside the field device to be set up.
 12. The method according to claim 11, wherein the prompting step comprises using a changeover switch to break the data link between the control device and the data memory inside the field device and to set up the data link between the data interface and the data memory inside the field device. 